Hey John NZ,
Sorry to hear about your results.
I work in Pharmaceuticals and come across this alot. I deal with patients blood results. When GGT Levels are high most people immediately think that the individual has a drink problem or has been consuming excessive amounts of alcohol, however your GP should know that this is not always the case.
High GGT Levels can indicate a number of other problems and only further tests from your GP can determine what this is.
Not to scare you.. but the most common ones i come across are hepititis, liver disorders or diseases and as a secondary indicator of obesity. I am not sure on this but i think it can also be a pre-indicator of diabetes. Also many drugs can increase your GGT levels.
I would really make sure that your GP does some further testing, this may determine why you have such a high level. Just a note, but some drugs can also lower GGT levels, so might be worth asking your GP if this is a possibility.
Anyway, Good luck, and if you want any other info, just ask
Caz xxx